Circuit for gaseous discharge tubes



arch 18, 1947. 1. R. DOSIO 2,417,742

CIRCUIT FOR GASEOUS DISCHARGE TUBES Filed Aug. 9, 194-4 4 Sheets-Sheet l j 2 1/0 nu 4T Halo Romano D05 0 INVENTOR A6 I ATTORNEY March 18, 1947. R, D0815 2,417,742

CIRCUIT FOR GASE'OUS DIS CHARGE TUBES Filed Aug. '9, 1944 4 Sheets-Sheet 2 5 J QQJA 0 d Y J L 6 112m: Romano D 5 1 INVENTOR 5- ATTORNEY 9 1947- l. R. DOSIO 2 ,417,742

CIRCUIT FOR GASEOUS DISCHARGE TUBES Filed Aug. 9, 1944 4 Sheets-Sheet 3 H l Eovyiano Doslo INVENTOR g ATTORN EY I I. R. DOSIO CIRCUIT FOR GASEOUS DISCHARGE TUBES March" is, 1947. 2,417,742

Filed Aug. 9, 1944 4 Sh eets-Sheet Bulb Rom n I INVENTOR ATTORNEY Patented ar. 18, 1 .247

CHREUIT F93. GASEQUS DISCHARGE TUBES ita ic Romano Dosio, Buenos Aires, Argentina, as-

signor to Ben Ruzin Rand, Buencs Aires,

Argentina Application August 9, 1944, Serial No. 548,677 In Argentina August 24, 1M3

4 Claims.

This invention relates to gaseous discharge tubes and more particularly to a circuit for instantaneously starting one or more gaseousdischarge tubes or fluorescent lamps.

As is known, one of themain difiiculties encountered in the utilization of gaseous discharge tubes or fluorescent lamps is that a relatively high voltage must be applied to the lamp electrodes in order to start an electric discharge therebetween and to ionize the gas contained in the lamp. On the other hand, once started, the initial voltage between the electrodes must be decreased to a considerably lower value since the internal resistance of the ionized lamp is relatively low and a high discharge current ccnsid erably reduces the life of the lamp.

It is known to provide the fluorescent lamps with one or more directly or indirectly heated electrodes which are connected to the alternating current supply source in series with a thermal or magnetic starting switch so that the first current impulses flowing through the electrodes heat the same to an electron emitting temperature. The emitted electrons ionize the gas included in thetube thus lowering the internal resistance thereof, so that the main voltage is sufficient to start the discharge between the elec trodes of the tube. After a predetermined period of time depending upon the lamp characteristics, the starter automatically interrupts the series connection of the electrodes which now operate as simple or "cold discharge electrodes. However, the starter which constitutes the main aux ilary element fluorescent lamp circuits, is a device of rather complicated construction the correct operation of which is considerably influenced by the ambient temperature, so t at the startin of fluorescent lamps included in this type of circuits is sometimes erratic.

It is also known to provide circuits for starting fluorescent lamps which do not utilize starters and in which the discharge electrodes of the lamps can be constituted by rods or plates of adequate material. However, the maiority of these circuits require equipment in form of transformers and inductors of special design and critical adjustment, so that the advantages gained by the elim nation of the starter are sometimes more than balanced by the cost of the auxiliary equipment and the larger mounting space required for the installation.

I have now found that a circuit for instantaneously starting one or more fluorescent lamps will be obtained by utilizing the voltage developed across the capacitive component of a series resonant circuit and by utilizing the inductive component of the same series resonant circuit as a current limiting device.

The circuit for gaseous discharge tubes or fluorescent lamps according to the present invention comprises an inductor and a capacitor contween the electrodes of the tube without a previous ionization of the gas by electrons emitted from the tube electrodes. Once ignited, the internal resistance of the lamp drops to a value considerably lower than the reactance of the capacitor and the inductor of the series resonant circuit operates as a current limiter device which maintains the current flowing through the lamp at a predetermined value.

Therefore one of the main objects of the present invention is to provide a circuit which will furnish instantaneous ignition of fluorescent lamps without the use of starters and filamentary electrodes in the lamps. A further object of the present invention is to provide a circuit for instantaneously igniting one or more fluorescent lamps comprising a minimum of circuit elements arranged in a very'simple circuit layout.

A still further object of the present invention is to provide a circuit for fluorescent lamps which will allow of the utilization of two fluorescent tubes without requiring additional auxiliary elements or parts.

A further object of the present invention is to provide a circuit for fluorescent lamps in which the colour ofthe emitted light may be adjusted by means of resistors or capacitors inserted in the circuit.

A still further object of the present invention consists in providing a circuit for fluorescent lamp-s wherein the amplitude of the voltage utilized for igniting the lamp can be regulated at will by means of inductors inserted in the circuit.

These and further objects and advantages of the present invention are described more fully in the detailed description which follows and are illustrated by the accompanying drawings, wherein:

Fig. 1 shows the basic layout of a circuit for one fluorescent lamp according to the present invention.

Fi 1a, discloses a modification of the circuit layout shown in Fig. 1.

Figures 2 to '7 and 2a to la inclusive each show a modification of a circuit for fluorescent lamps arranged in accordance with my invention, and

Fig. 8 shows a further modification.

In the drawings similar parts or elements are designated with similar reference numerals or characters.

Referring now to the diagram shown in Fig. 1, it can be seen that the basic circuit for fluorescent lamps according to my invention comprises an inductor a, having its end I connected by means of conductor 2 to input terminal 3 of the circuit, while the other end 4 of inductor a is connected through conductor 5 to one electrode of a capacitor b, the other electrode of which is connected to the other input terminal 6 of the circuit by means of a conductor 1, input terminals 3 and 6 being connected to an adequate alternating current supply source during the operation of the lamp.

A gaseous discharge tube or fluorescent lamp 0 is connected in parallel with capacitor b, and each end of the discharge electrodes 8 of the tube is directly connected to one of the electrodes of capacitor b by means of respective conductors 9.

Inductor a and capacitor 21 are designed to constitute a series resonant circuit tuned approximately to the frequency of the alternating current supply source to which input terminals 3 and 6 of the circuit are applied.

When applying the main voltage to the circuit according to the present invention, the cold fluorescent lamp 0 constitutes a very high resistance to the alternating current flowing in the circuit and does not change the impedance of the capacitor across which it is connected. The alternating current hence flows through inductor a and capacitor b and the oscillating voltage developed across the latter circuit element is sumciently high to start an electric discharge between during the starting period the sum of the inductance of both windings, together with the capacitance of capacitor 0, constitutes a series resonant circuit, and the voltage developed across capacitor 11 thus being suificient to start the electric discharge between the electrodes 8 of the lamp.

However, as soon as the lamp has been ignited, the current circulating in the circuit saturates one or both windings of inductor a thus lowering their inductance so that the high current intensity required for operating the lamp, is easily obtained.

Referring now to the circuits disclosed in the Figs. 2 to '7 and 2a to la inclusive, it can be observed that each of these circuits comprises the basic series resonant circuit shown in the drawing of Fig. 1a and which includes one gaseous discharge tube 0, with the difierence that the secondary winding H] of transformer T, the primary winding of which constitutes inductor a of the series resonant circuit, is connected to a secondary gaseous discharge tube d, this circuit thus supplying the required current for two gaseous discharge tubes or fluorescent lamps with the same number of circuit elements.

In fact, as can be observed in the drawing of Fig. 2, the basic series resonant circuit corresponding to main discharge tube a is formed of input terminal 3, conductor 2, primary winding a of transformer T, conductor 5, capacitor 79, conductor I and the other input terminal 6, main discharge tube a being connected in parallel with capacitor b.

The supply circuit for the secondary gaseous discharge tube (1 is formed of the above-mentioned secondary winding lil connected with its extreme 42 to input terminal 3 by means of conductor 14, while the other extreme i! thereof is connected by means of conductor l5 to one of the discharge electrodes 8 of secondary tube d, the other discharge electrode of which is coupled to the other input terminal 8 of the series resonant circuit by means of conductor 16.

Hence, the basic series resonant circuit constituted by the primary winding a of transformer the discharge electrodes 8 which ionizes the g 45 T and capacitor b connected in parallel with the included in the fluorescent lamp.

Due to the ionization of the gas, the internal resistance of the lamp drops to a value considerably lower than the impedance of capacitor b,

main electric discharge tube c, and the supply circuit for the secondary electric discharge tube d which includes the secondary winding ID of transformer T, are connected in parallel.

so that the main portion of the current flows When applying the mains voltage to the circuit through lamp 0 and inductor a which acts as current limiter. Fluorescent lamp 0 is now in an operating condition and the discharge between the electrodes thereof will be maintained as lon as the circuit remains connected to the alternating current supply source.

Hence, it can be seen that in the circuit according to my invention an almost instantaneous and automatic ionization and starting of the fluoshown in Fig. 2, the oscillating voltage developed across capacitor b causes the ionization of the gas included in the tube to, as already explained hereinbefore.

At the same time the oscillating voltage developed in the primary Winding a of transformer T induces, as known, a corresponding secondary tension in winding iii of the transformer and this secondary tension has an amplitude sufficient to rescent lamp is obtained as soon as the mains cause an electric discharge between the electrodes voltage is applied to the circuit.

The operation of the circuit shown in Fig. 1a is similar to that disclosed in Fig. 1, with the sole difierence that inductor a is formed by the 8' of discharge tube d, the windings of transformer :1 being designed and adjusted so that the ionization and ignition of the gaseous discharge tubes 0 and dis completed almost simultaneously.

primary winding of atransformer T, the second- 5 The current circulating in the basic series ary winding 10 of which is loaded by means of a resistor l3 connected to the extremes H and I2 of the winding, so that the impedance of inductor a can be conveniently adjusted by varying load resistor I3.

When the fluorescent lamp 0, used in the circuits shown in Figs. 1 and la, is of the high current intensity type, inductor a can be split in two series connected windings separately mounted resonant circuit, i. e. the current which in a certain moment passes from input terminal 3 to primary winding :1, gaseous'discharge tube 0, and other input terminal 6 or vice versa, causes a con- 0 siderable reduction of the inductance of the primary winding a which, after starting, operates as a current limiting reactance with respect to gaseous discharge tube 0. A similar phenomenon occurs in the supply circuit of the secondary on a common core having an air gap, so that gaseous discharge tube cl, since the current circulating through the tube automatically reduces the inductance of secondary winding It.

lhe operation and general layout of the circuit shown in Fig 2a; is similar to that of the circuit shown in Fig. 2, with the only difference that in the former extreme iii of secondary winding iii of transformer T is connected to input terminal ii by means of a conductor ii, while the electrode E of the same secondary discharge tube at, instead of being coupled to input terminal ii as shown in the embodiment of the inv ntion disclosed Fig. 2, is connected to input terminal 3 of the basic series resonant circuit by means of a conductor 58, as shown in the circuit of Fig. 2a, the opposite discharge electrode 8 of tube at being connected to the other extreme ll of secondary winding it through a conductor it.

Therefore, it will be evident for those skilled in the art, that the operation of the circuit shown in Fig. 2a, is exactly similar to that of Fig. 2 with respect to the instanteous starting and automatic ignition of the gaseous discharge tubes and cl, since the primary secondary windlugs a and E 3 of transformer '53, although being connected in a different manner, operate as already explained with reference to the circuitshown in Fig. 2.

The circuits shown in Figs. 3 to 7 and 3a to To inclusive, are based on the circuits disclosed in Figs. 2 and 211 respectively, and refer to several modifications of the basic series resonant circuit.

It has been found in practice, that in spite of the fact that like voltages are applied to the gaseous discharge tubes 0 and (Z, a slight difference in the colour of the emitted light is sometimes to be found and it has been determined that generally this difference is due to variations in the phase of the alternating current circulating through the tubes.

Therefore, in order to improve the operation of the circuits comprising two gaseous discharge tubes according to the present invention, and more particularly to obtain like colours of the light emitted by the tubes, a resistor 59 or It can be inserted in series with a capacitor b and pa'allel to the corresponding discharge tube 0, as can be observed in the circuits shown in Figs. 3 and 3a, in which resistors E9 or 59' together with capacitor b constitute a phase shifting circuit.

The adiustrient of the colour of the light emitted by the secondary gaseous discharge tube (1 can be obtained by connecting a capacitor 25% or Ell across the ex remes i l and l 2 of the secondary winding ill of transformer T (Figs. 4 and 4a), and it will be evident that similar condenser 25 or 2! connected across the primary winding a of transformer T 5 and 5a), will have the same eifect on the colour of the light emitted by the main gaseous discharge tube 0, since these condensers shift the phase of the current flowing through the corresponding tube.

As already explained hereinabove, the instantaneous starting of the gaseous discharge tubes 0 and d is obtained by means of the high oscillating voltage developed across the corresponding element of he basic series resonant circult according to the present invention. However it has been noticed that this voltage may acquire so large an amplitude as to destroy not only the insulation between the primary and secondary windings of tranfornier T, but also considerably reduce th life of the tubes by producing sputtering of electron emitting material provided on the discharge electrodes. Therefore, in designing transformer T, the primary and secondary windings thereof are generally constructed so as to have individual inductances and a mutual coupling which will facilitate the generation of a relatively low voltage for automatically starting the gaseous discharge tubes included in the circuit.

However, sometimes it may be convenient to provide additional means for limiting the osci1lating voltage, and such means can be formed of ctor or 22 connected in parallel with the n-ain gaseous discharge tube 0, as can be observed in the circuits shown in Figs. 6 and 6a respectively.

Inductor 22 or 22' constitute a load for the basic series resonant circuit according to the resent invent-ion and thus limits the amplitude 01 the oscillating voltage developed therein which, hence, cannot reach values causing the destruction of the insulation between the windings of transformer or the modification of the discharge electrodes of the tubes.

Instead of connecting the voltage limiting in ducts-r 22 or 22 across main discharge tube 0, it can be inserted between the extremes ii and l of secondary and primary windings ill and a, respectively, of transformer T, as can be observed in the circuits shown in Figs. 7 and 7a. In this position inductor 22 or 22 operates as an amplitude limiter for the oscillating voltage developed in the circuit for fluorescent or gaseous discharge lamps according to the present invention.

If relatively long gaseous discharge tubes 0 and d were to be utilized with one of the circuits according to the present invention, a step-up autotransforrner TT can be inserted between the alternating current supply source and input terminals 3 and S of the circuits, as can be seen in the drawing of Fig. 8.

While I have indicated and described several systems for carryin my invention into effect, it will be apparent to one skilled in the art that my invention is by no means limited to the par- ;c lar organizations shown and described, but many modifications may be made without departing from the scope of my invention, as set forth in the appended claims.

I claim:

1. A circuit for gaseous discharge tubes, comprising a source of alternating current, an inductor and a capacitor connected in a series resonant circuit and a main gaseous discharge tube connected in parallel with said capacitor, said inductor being constituted by the primary winding of a transformer is directly connected to one input terminal of the circuit while the other extreme of said secondary winding is connected to one discharge electrode of a secondary gaseous discharge tube, the other discharge electrode of which is connected to the other input terminal of the said series resonant circuit.

A circuit for gaseous discharge tubes, comprising a source of alternating current, an inductor a capacitor connected in a series resonant circuit and a main gaseous discharge tube connected in parallel with said capacitor, said inductor being constituted by the primary winding of a transformer the secondary winding of which is directly connected with one eX- trerne to one input terminal of the circuit, while the other extreme of said secondary winding is connected to one discharge electrode of a seethe secondary winding of which ondary gaseous discharge tube, the other discharge electrode of which is connected to the other input terminal of the said series resonant circuit, and a resistor inserted in series with said capacitor connected in parallel with said gaseous discharge tube.

3. A circuit for gaseous discharge tubes, comprising a source of alternating current, an inductor and a capacitor connected in a series resonant circuit and a main gaseous discharge tube connected in parallel with said capacitor, said inductor being constituted by the primary winding of a transformer the secondary winding of which is directly connected with one extreme to one input terminal of the circuit, while the other extreme of said secondary winding is connected to one discharge electrode of a secondary gaseous discharge tube the other discharge electrode of which is connected to the other input terminal of the said series resonant circuit, and a capacitor connected in parallel with said secondary winding.

4. A circuit for gaseous discharge tubes, comprising a source of alternating current, an inductor and a capacitor connected in a series resonant circuit and a main gaseous discharge tube 8 connected in parallel with said capacitor, said inductor being constituted by the primary winding of a transformer the secondary winding of which is directly connected with one extreme to one input terminal of the circuit, while the other extreme of said secondary winding is connected to the discharge electrode of a secondary gaseous discharge tube, the other discharge electrode of which is connected to the other input terminal of the said series resonant circuit, and an inductor connected to the extremes of said primary and said secondary windings remote from the input terminals of the said circuit.

ITALO ROMANO DOSIO.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,301,840 Yost' Nov. 10, 1942 2,339,307 Warsher Jan. 18, 1944 2,236,039 Sola Mar. 25, 1941 2,231,999 Gustin Feb. 18, 1941 2,291,355 Simmon July 28, 1942 

